ABSTRACT The 50% formic acid fumigator (FAF) for varroa mite control was developed as part of a SARE grant (1999 to 2001). The fumigator was evaluated for five years on 123 colonies in five bee yards in Connecticut, Maryland and West Virginia. Treatments eliminated all mites on adult bees and 90 to 95% of mites in sealed brood cells. Very few brood or new young adult bees were injured by the treatment. The fumigator is a simple design and the overall cost of treatment is about $1.00 per hive or less. The 50% FAF was less toxic to bees compared to other treatments using 65%. 80% or 90 % formic acid (FA). The fumigator was applied for 18-24 hours, when ambient temperatures were between 10-30° C. In the USA, one treatment in mid-August to mid-September was effective and usually all that was required each year. The 50% FAF used with other essential oil treatments including salt-grease patties with wintergreen, feeding 1:1 syrup with Honey-B-Healthy7 (spearmint and lemongrass essential oils), and use of screened bottom boards together provide a synergistic effect to keep mite numbers at a relatively low level, as part of an integrated pest management (IPM) system.

[Show abstract][Hide abstract]ABSTRACT: We used the 50% formic acid fumigator to treat 51 honey bee colonies in Florida on April 2, August 16 and October 23, 2006 and January 2, 2007, to control varroa mites. Treatments consisted of 90 to 110 ml of 50% formic acid mixed with 15 ml of Honey-B-Healthy™ essential oil concentrate to prevent queen losses. The fumigator was applied during daylight hours to each hive, screened bottoms were covered, openings taped over, and the entrance reduced to 3/8" by 3 1/2" (0.95 cm x 8.9 cm) and removed the next day after from 17 to 23.3 hours. Average mortality of varroa mites in capped drone cells was 93% (92.8% to 98.8%) (after adjustment for Abbott's correction for control mortality). Capped drone cells in old black comb had the lowest mortalities (66% to 84%): less of the 50% formic acid vapor was able to penetrate the thicker cappings.

[Show abstract][Hide abstract]ABSTRACT: With the recent decline of honey bees, Apis mellifera (L.) (Hymenoptera: Apidae), there is a need for alternative or supplemental crop pollinators, such as Osmia cornifrons (Radoszkowski) (Hymenoptera: Megachilidae). However, O. cornifrons propagation could be impeded by a cleptoparasitic mite, Chaetodactylus krombeini Baker. We investigated the effects of formic acid and wintergreen oil on mortality of C. krombeini hypopi and O. cornifrons adults by determining the lethal concentration of each compound on each species. On average, >4.8 and >1.8 h were required to cause mortality in O. cornifrons adults when <2,473.5 ppm of formic acid and wintergreen oil was applied as a fumigant, respectively. When the two chemicals were directly applied to the exoskeleton of O. cornifrons adults, 353.4 ppm of wintergreen oil caused bee mortality within 10 min; however, no mortality was found with any formic acid application attempted. Mortality of C. krombeini hypopi occurred 5 and 10 min after application of >176.7 ppm of formic acid and wintergreen oil, respectively. Estimates of LC50 for C. krombeini hypopi treated with formic acid and wintergreen oil were 54.3 and 271.3 ppm, respectively. This study showed that C. krombeini could be controlled effectively without inducing O. cornifrons adult mortality based on concentration and duration of fumigation.

[Show abstract][Hide abstract]ABSTRACT: Controlling populations of varroa mites is crucial for the survival of the beekeeping industry. Many treatments exist, and all are designed to kill mites on adult bees. Because the majority of mites are found under capped brood, most treatments are designed to deliver active ingredients over an extended period to control mites on adult bees, as developing bees and mites emerge. In this study, a 17-h application of 50% formic acid effectively killed mites in capped worker brood and on adult bees without harming queens or uncapped brood. Neither acetic acid nor a combined treatment of formic and acetic acids applied to the West Virginia formic acid fumigator was as effective as formic acid alone in controlling varroa mites. In addition, none of the treatments tested in late summer had an effect on the late-season prevalence of deformed wing virus. The short-term formic acid treatment killed > 60% of varroa mites in capped worker brood; thus, it is a promising tool for beekeepers, especially when such treatments are necessary during the nectar flow.

Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Page 1

FORMIC ACID FUMIGATOR FOR CONTROLLING HONEY BEE MITES IN BEE HIVESJames W. Amrine Jr.1 and Robert Noel21. Division of Plant and Soil Sciences, G-168 Agricultural Sciences Buildinng, West Virginia University, P.O. Box6108, Morgantown, WV 26506-6108. USA (jamrine@svu.edu); 2. Fort Hill High School, 108 Blackiston Avenue.Cumberland, MD 21502, USA (rcnoel@atlanticbb.net).ABSTRACT - The 50% formic acid fumigator (FAF) for varroa mite control was developed aspart of a SARE grant (1999 to 2001). The fumigator was evaluated for five years on 123 coloniesin five bee yards in Connecticut, Maryland and West Virginia. Treatments eliminated all miteson adult bees and 90 to 95% of mites in sealed brood cells. Very few brood or new young adultbees were injured by the treatment. The fumigator is a simple design and the overall cost oftreatment is about $1.00 per hive or less. The 50% FAF was less toxic to bees compared to othertreatments using 65%. 80% or 90 % formic acid (FA). The fumigator was applied for 18-24hours, when ambient temperatures were between 10-30? C. In the USA, one treatment in mid-August to mid-September was effective and usually all that was required each year. The 50%FAF used with other essential oil treatments including salt-grease patties with wintergreen,feeding 1:1 syrup with Honey-B-Healthy7 (spearmint and lemongrass essential oils), and use ofscreened bottom boards together provide a synergistic effect to keep mite numbers at a relativelylow level, as part of an integrated pest management (IPM) system.Key Words: Formic Acid Fumigator, Varroa destructor, Acarapis woodi, essential oils, saltgrease patties, screened bottom boards, Apis mellifera, Honey Bee, Honey-B-Healthy7, IPM.INTRODUCTIONThe varroa mite, Varroa destructor (Anderson and Trueman, 2000)(Mesostigmata:Varroidae) and the tracheal mite, Acarapis woodi (Rennie, 1921) (Prostigmata: Tarsonemidae),are the most damaging pests of the western honey bee, Apis mellifera L. (Hymenoptera: Apidae)in the world today. Since their introduction to North America in 1984 (tracheal mite) and 1987(varroa mite), virtually all wild colonies have been eliminated, and many beekeepers, bothhobbyists and professionals, have abandoned the profession. Those who remain have the hardresponsibility for maintaining healthy bee colonies for pollination of crops and for the generalwelfare of the environment.Organic acids and essential oils now play a bigger roll in integrated pest management ofparasitic mites and pathogens of honey bees, because of development of resistant mites andpathogens. The Varroa mite has become resistant to synthetic acaricides (Pettis 2004). Wedeveloped our four-fold treatment protocol (Amrine et al. 1996; Noel and Amrine, 1996) of: (1)screened bottom boards, (2) wintergreen/salt grease patties (Sammataro et al., 1996; Sanford,1995), (3) feeding essential oil concentrate, Honey-B-Healthy7 (HBH) (Noel 2006), and (4) the50% formic acid fumigator (Amrine & Noel 2001), to reduce and control honey bee mites usingessentially natural ingredients. Five years of using the improved version of the formic acidfumigator showed that only one or two, 24 hr treatments in mid-August to mid-September(middle Atlantic States Climate) controlled both Varroa destructor and the less destructivetracheal mite, Acarapis woodi.For a full description of the other three protocols, please see our websites:

Page 2

http://rnoel.50megs.com/2000/index.htm and http://www.wvu.edu/~agexten/varroa.Abbreviations and acronyms used in this report: C - Centigrade, cm - centimeter, CT- Connecticut, F - Fahrenheit, FA formic acid, FAF, formic acid fumigator, FA-HBH - formicacid-Honey-B-Healthy7, FL - Florida, HBH - Honey-B-Healthy7, MD - Maryland, PMS -parasitic mite syndrom, Qt - quart, WV - West Virginia, WVU - West Virginia University, “ -inch. MATERIALS AND METHODSScreened bottom boards (using 1/8" (0.375 cm) hardware cloth) for varroa mitecontrol (Horn, 1987, Pettis & Shimanuki 1999) were used on all of our colonies. For our trials,we made an opening in the back of the bottom board, below the screen, for inserting home-madedetector boards [12 1/4" x 16 7/8" (31.15x.9 cm) white demonstration board, coated withpetroleum jelly (Vaseline7)] which could be replaced with a sheet of masonite for fumigation.Screened bottom boards take advantage of the natural, 10-20% mite fall that occurs throughoutthe year. Without vaseline, the mites will crawl back up onto the bees.The 50% formic acid fumigator, FAF, (Figs. 1-6) has two parts: an inner fumigator frame and anouter supporting frame. The outer surface has the same dimensions as a Langstroth honey superor 18" x 16 3" (45.72 x 41.275 cm). The inner fumigator frame (Fig 3) is 17 2@ long by 12 2@wide (44.45 x 31.75 cm), made with :@ x 7/8@ (1.9 x 2.22 cm) wood molding (see details inFigs. 4-5). The upper surface is covered with 1) standard aluminum or plastic window screen toprotect the absorbent pad from the bees on the underside, 2) an absorbent pad (non-wovenundergarment, Kendall7 7174 bed pads, available from hospital supply stores or drugstores) withthe absorbent surface down, and 3) a sheet of aluminum >flashing= (available from homeimprovement stores) as a top cover, screwed into place with 4 screws, overlapping the two sidesof the fumigator frame by 2A (1.27 cm). This inner fumigator frame is nailed (from the ends)into a 1 :@ x :@ (4.45 x 1.9 cm) outer supporting frame, with the same outer dimensions as aLangstroth honey super (see above) forming two 3/8@ (0.9 cm) beeways on each side, with thetop, flashing surface of the inner fumigator recessed 3/8" (0.9 cm) below the top surface, andwith the bottom of the inner fumigator frame about 5/16@ (0.79 cm) above the bottom margin.This construction provides an important air cavity, Athe activation cavity@ (Fig. 6), 1 3@ deep x12 5/16@ x 17@ (3.175 x 31.27 x 43.18 cm), below the absorbent surface and just above the broodframes. In American style hives, the tops of the brood frames are recessed about 3/16" (0.476cm) below the super margin, and allowance for this additional space will have to be made inBritish- or European-style hives.Application - Before treatment, we taped over all holes, openings, etc., and we used asolid bottom board, or sealed the bottom with an aluminum, plastic or masonite sheet. Theentrance was reduced to a small central opening 7/8" (.95cm) x 3.5" ( 8.9 cm) (Fig. 7).At time of application (see below) we poured 2.9-3.4 ozs. (85-100 ml) of 50% formicacid (depending on the size and number of the brood chamber(s)), mixed with 10-20% (0.5 to0.67 ozs or 15 to 20 ml) of Honey-B-Healthy7 (mixed at time of application1) onto the pad andplaced the fumigator on top of the upper brood chamber, with the absorbent material down. The

Page 3

amount of formic acid mix used depended on the number and depth of the brood chambers; eg.,we used 2.9 ozs (85 ml) for a single deep chamber, 3.2 ozs (90 ml) for double Illinois chambersor a deep + shallow, 3.21 ozs (95 ml), and for double deep chambers (3.38 ozs or 100 ml), etc.Fumigation is done when the ambient temperature is between 17-31?C (60-85? F). Thefumigator is placed on the hive at about 12:00-18:00, and taken off at about 12 noon the next day(18 -24 hrs. exposure). We kept detector boards on the hives for 13-14 days in order to samplemite drop during one capped brood cycle (Fig. 8D, Fig. 9).Summary of Application:1. Ambient Temperature should be 60 to 90? F (15.5-32.2? C).2. Apply treatment between 13:00 & 18:00 (1-6 PM), ideally mid-August to mid-September.3. Manage all brood frames in one or two brood chambers.4. Thoroughly mix 85 ml (2.9 oz) of 50% FA solution with 15 ml (1/2 oz) HB; pour ontoabsorbent pad in fumigator. Place above upper brood chamber.5. Tape all openings shut; if using screened bottom board, use solid Bottom Board or cover thescreen with masonite, plastic or aluminum sheet.6. Reduce entrance to 3@ x 3/8@ (7.5 x 1cm) at center.7. Remove fumigator the next day between 12:00 & 18:00(noon and 6 PM).In most cases, only one treatment is needed per season. We often go two seasons betweentreatments, depending on # of infested brood cells (and # of incoming mites from dying and/orwild colonies).ResultsAfter applying the FAF, the bees quickly began to fan the air through the brood nest andout of the small bottom entrance; you could easily feel the air and smell the formic acid comingout of the central entrance. During the treatments, average temperatures were 93-94?F (33.9-34.4? C) between the full brood frames, 92-93?F (33.3-33.9? C) just below the fumigator at thecenter of the hive, and the air exiting the entrance was nearly always 90?F (32.2?C).Temperatures were lower in the weaker colonies with just a few frames of brood. We hadexcellent mite kill on most hives in all of our preliminary trials (Table 1), including mites insidesealed brood cells. Because of the addition of HBH, we saw very little interruption of queenperformance, and no balled queens in the WVU trial. In August, 2000 we conducted similartrials with formic acid only (no HBH), at the same concentration and amount, and lost queens in6 out of 24 (25%) colonies (Connecticut). The Cumberland, MD, preliminary trial (41 colonies),at the same time and same doses of FA, but with HBH, had two queen losses or 4.3% loss, whichmay have been due to failing queens. The WVU trial of 82 colonies in September 2000, usingthe same doses of FA, but with HBH, resulted in no loss of queens. In 2001, in Cumberland,MD, three queens in 46 (5%) FA-HBH treated colonies were lost. Another trial in Cumberland atthe same time, of 31 colonies using synthetic acaricides (Apistan & CheckMite) showed a 6%queen loss (no HBH). We have used our 50% formic acid fumigator at WVU and Cumberland,MD, for the past five years with the same, consistent results. In addition to adding the HBH tothe formic acid mix, spraying the bees and brood area with 1:1 sugar syrup with 20 ml ofHBH/Qt (0.95 l) helps to prevent queen loss.

Page 4

Queen losses were reduced from 25% to about 5% or less with some trials showing 0%losses, while obtaining a 90-95% kill of Varroa on the bees and in the cells in treatments lastingless than twenty-four hours. Some open brood, and hatching young bee losses could not be totally eliminated. Thisminimal loss of a few hundred bees at most had no detrimental effect on colony strength(40,000-60,000). The treatments stopped varroasis in thousands of brood cells and allowed broodto hatch as healthy adults, free of deformities and disease. Large numbers of clean, healthy broodare needed for a colony to successfully overwinter. The potential loss of a handful of bees isminimal when compared to the thousands of bees saved by the treatment.Table 1. Results of 50% FAF-HBH treatment of bee hives at WVU Horticulture Farm, 18 Sep 2000;numbers of dead VM on sticky cards. Hives were maintained on two Illinois-style brood chambers,with 7 frames of brood in each hive. HFH: Hort Farm Homestead; bees purchased from WeaverApiaries, Navasota, TX, May 2000. RNH-1: Robert Noel hive treated at the same time. All had beentreated with 4 weeks exposure to “low acid” by wicks into brood chamber from reservoir below hivecontaining 40% FA and 10% acetic acid (had no effect on VM). We estimated an 80% reduction inVM populations.Hive # 24 hrs+3dHFH-11507 4257HFH-2 6912223HFH-3 774 3804HFH-4 4774179HFH-5 1129 3024HFH-6 31748748HFH-8 1184 3039HFH-9 11172694RNH-1 544 540Avg. 11773612DiscussionBy using a lower concentration of formic acid, approximately 44% after HBH is added,we have reduced the chance of injury to bees. This new, improved 50% Formic Acid Fumigator has inreased the efficiency of formicacid in the following ways: 1) A recessed air space is provided just above the upper brood chamber within the fumigator.Heated air from the brood rises into this enclosed space which has a controlled 92? F (33.3? C)temperature. We call this space the Aactivation cavity.@(Fig. 6.)2) The upper surface of this space has an absorbent material saturated with a 44.1% FA-HBHmix, overlying the entire brood area. The FA is much heavier than air (specific gravity of 1.11)sinks to the bottom board and does not rise. This is probably why so many investigators hadvariable results when placing small pads of FA on the bottom board, in the back corner of

Page 5

colonies, in modified frames placed between brood cells, or in small pads on top of the broodsupers, but with no controlled heated or evaporation space and with a fully open entrance.Placement of the FA-HBH mix about 1.25" (3.175 cm) above the upper brood frames is criticalfor the performance of this fumigator.3) By reducing the entrance to 3/8" x 3.5" (0.95cm x 8.9 cm)(Fig. 7), and by having only two3/8" (0.9 cm)bee ways on the sides of the fumigator (Fig. 3), allows the FA-HBH mix to saturatethe hive atmosphere which then penetrates all capped brood cells, killing 90-95%+ of the mitesin most colonies in less than 24 hours. Dead mites can be found in brood cells during the next13-14 days, and these accumulate in dense bands on the detector board during this time. (Fig.8B,C).4) The upper aluminum sheet prevents the warm air from being lost to upper supers (boxes offrames for honey storage above brood chambers) (Fig. 2).Thus, warm air rises from the brood and activates the FA-HBH in the absorbent padcausing evaporation. The pad can hold 150 ml of solution without dripping. The bees respondwith a roar of fanning, and the FA-HBH saturated air circulates throughout the brood space andeventually exits the small entrance opening. The circulating air is warm (90?F, 32.2? C) when itexits; the FA penetrates capped cells, killing mites inside, but not the brood. Within 24 hrs,virtually all of the FA has evaporated and the fumigator can be removed. The more brood frames, the better the performance of the fumigator. We feed HBH to thebees in August to stimulate brood production prior to fumigation with the FA.The detector board should be left on for 13 days (14 days for drones) to get an estimate ofthe mite population and mortality. This period corresponds to the number of days required forone cycle of capped brood to complete development and exit cells. As bees exit the cells, deadmites and debris fall between the frames, through the screened bottom, and onto the detectorboard below. Some colonies produced counts exceeding 3,000 mites on a single detector boardin 13 days. We have 426 boards (Fig. 8B-E) taken from as many treatments, and it is verysatisfying to see the 1000's of dead mites in the petrolatum.For most hives, one treatment usually places the colonies far below injury level forseveral months (fewer than 5 of 100 examined drone cells infested). Occasionally, a secondtreatment may be needed about two weeks after the first. Honey-B-Healthy7 and Queen Preservation - Honey-B-Healthy7 is a mixture ofspearmint and lemongrass essential oils with water, lecithin and a trace of sodium laurel sulfateto stabilize the product. It has a shelf-life of several years. It is formulated so that one teaspoon(5 ml) of HBH delivers 0.5 ml of spearmint oil and 0.5 ml of lemongrass oil to the targetsolution, which is usually a quart of 1:1 sugar: water syrup. We compared many essential oils intreatments of colonies with parasitic mite syndrome (PMS) in 1995 and 1996; we found thatwintergreen and spearmint were excellent at reducing the PMS and allowing colonies to producenormal healthy bees. Spearmint always gave superior results. However, honey bees are notattracted to spearmint oil syrup; they may take a week to consume the spearmint syrup. BobNoel experimented with many additives to try to get the bees to feed on spearmint-syrup; he metwith success with lemongrass oil. The combination was excellent and the bees took it rapidly;

Page 6

we timed a number of colonies that were eager to forage, and they often removed a single quartin 4 hours. In cooler weather, or when the bees do not need to forage, the syrup lasts longer.Essential oil components in Honey-B-Healthy7 modify the effect of Formic Acid (FA)treatment on bee hives, such that queens are not lost. This aspect is extremely important for anybeekeepers using formic acid to treat varroa mites.Fumigator evolution - In 1998-2000, we experimented with formic acid fumigationusing shallow honey supers containing absorbent cotton on an aluminum screen attached to thebottoms; various concentrations of FA were placed on the cotton and the supers were placed onthe hives. In September-October 2000, the original, thin fumigator was developed which wasequivalent to just the inner frame described above, our 24-hour fumigation technique workedextremely well for us in 60 - 70% of the hives treated. In 2001 we developed the presentfumigator with the larger above brood space and increased the efficacy to about 90% of coloniestreated. The present design has not changed since 2002.Formic Acid Handling and Storage - Anyone repeating these treatments shouldtemporarily remove honey supers, wear rubber gloves, use eye protection and have wateravailable; do not inhale fumes (formic acid will enter the blood from the lungs and can beharmful to the liver). The 50% formic acid was mixed ahead of time; it can be stored indefinitelyprior to use; but do not add the HBH until time of application. We always mixed the formic acidand HBH in an open, outside area or in a fume hood, and we used a lowcost hydrometer ($5 atwww.williamsbrewing.com) to obtain exactly 50% FA (sp. grav. = 1.110). The hydrometer wasneeded because we found considerable variation in strength of formic acid in containers that wepurchased; some were off as much as 30%. This may be one reason that published reports gavevariable results for the use of formic acid. Beekeepers must also be aware that formic acidobtained from some commercial sources may contain heavy metal contaminants; these may beharmful to the bees, to humans and to the environment. Always inquire about the possibility ofheavy metal contaminants. Keep the formic acid in a tightly sealed container and read the safetylabel and the Material Safety Data Sheet (MSDS 2006). Store it in a cool, dry ventilated areaaway from sources of heat or ignition. Protect against physical damage. Store away from directsunlight. It is strongly corrosive and should be kept in containers made of 316 stainless steel,glass, ceramic or similar corrosion-resistant materials. Containers of formic acid may bedangerous when empty since they may have product residues; always rinse empty containersthree times. Obsereve all warnings and precautions listed for formic acid (MSDS, 2006).Cost - Formic acid is relatively cheap. Our supplier in Roanoke VA (Chemicals &Solvents, Inc., 1140 Industry Ave., SE, Roanoke, VA; phone: 703-427-4000 ) sells FA in fivegallon containers for $51.67 (March 2006), which can be stored indefinitely. Purchased FA canvary from 90% to 98% FA; when diluted to 50%, 5 gallons of FA would make about 9.7 gallonsof mix. Using it at 90 ml per hive, five gallons of FA would make up about 408 treatments. Onaverage, the cost of treating one hive is about US $1.00 or less after figuring in the cost of thesugar syrup and the Honey-B-Healthy7.Negative aspects of using formic acid - It is toxic and can cause skin and liver problemsif the operater is careless, especially with the concentrated acids (MSDS, 2006). However, the

Page 7

advantages and simplicity of using FA certainly outweigh the disadvantages. It is found naturallyin honey in small amounts (Bogdanof et al., 2002). Beekeepers should remove honey supersduring treatments; they can be replaced the next day after the fumigator is removed. There isoccasional, minor brood injury and we noticed a small kill of young emerging workers andemerging drones in 6 treatments conducted in April, 2005: about 25-100 bees per populouscolony. However, it is effective on tracheal mites as well as varroa mites, and no mite resistancehas so far been reported for Formic Acid treatments.Why does the formic acid fumigator work? - The strong hydrogen bonds in formic acid causethe vapors to act more like liquids than like gasses (Laffitte, 2006). Concentrated solutions offormic acid, 60%, 65%, 80%, 85% and 90% (used in many different formic acid treatments inEurope and North America (Anonymous, 2002; Becker, 1994; Imdorf et al., 1999; Chapleau,2003)), act like liquids, not vapors when they evaporate. The dense vapors flow directly to thebottom of the hive, and out onto the ground, where they kill grasses and weeds. When mixedwith water at 50%, the resultant vapor acts more like a gas, does not sink as quickly, and has alonger ‘hang time’ in the brood nest. But it is still a fluid-like vapor that has the ability otpenetrate the brood cappings and to kill the varrroa mites within the cells. Why does it killvarroa mites and tracheal mites but not honey bees? Mites have cuticles more permeable to FA;formic acid directly enters their hemolymph, acidifying the acarine brood, killing the mites.Honey bees have a cement layer covering the epicuticle which repels many external chemicalslike FA. This cement layer is thinner and less effective in some larvae and newly emerged adultbees which is why we see some mortality (100-500/colony) of small or recently eclosed larvaeand of newly eclosed workers and drones. The vast majority of the bees are not harmed by 50%FA fumigation.CONCLUSIONSThis fumigator is inexpensive, simple to use, and very effective if used on colonies with manybrood frames and when ambient temperatures are between 65-86? F (18-30? C). We believe thatState Departments of Agriculture and (USA) should make an exemption to apiary laws to allowuse of the 50% FAF to treat colonies infested with Varroa mites. We envision a centralbeekeeper=s cooperative, regulated or licensed by the state, who purchases the concentratedformic acid in 5 gallon or 15 gallon containers, diluting it accurately to 50% FA, and providing itto beekeepers in small sturdy containers for treatment of their bees. Another effective way toregulate the treatments would be for Beekeeping Clubs and Associations to function as acooperative as described above. They would buy the concentrated FA, dilute it accurately to50%, and sell small containers of the solution to beekeepers needing the treatment. They couldeven manufacture 10 or 20 of the fumigators and have them on hand to loan to the beekeepers. Details of the construction of the fumigator are provided so that it can be made for a fewdollars, within a few hours, by anyone familiar with woodworking techniques. We want to makethis fumigator public knowledge in order to benefit beekeepers and the honey bee. The basicfumigator and its concepts were presented in our research report to SARE (Amrine & Noel2001), and thus deem its design to be public property. We have no intention of trying to obtain apatent on this useful device. Infringement of this intellectual copyright property is prohibitedwithout proper acknowledgement given to the inventors of the device.

Page 8

The once simple hobby of beekeeping is rapidly becoming the “science of beekeeping”with knowledgable beekeepers who can find and identify pests, and know when and how toapply various treatments to control them. Because varroa mite is now resistant to syntheticacaricides, a disciplined, year-round treatment protocol will have to be followed, combining theuse of organic acids and essential oils, or similar techniques, to control parasitic mites andpathogens in honey bees. Our united control efforts will vary by region, with adjustments madefor the various climatic conditions and beekeeping practices.Finally, mites may not develop resistance to essential oils and formic acid as withsynthetic acaricides. Formic acid has been used in Europe for about 25 years with no knownreport of mite resistance. Caution - When working with formic acid, wear gloves, eye protectors and have plentyof water available for flushing if needed. Remove honey supers before fumigation. Be sure tohave good ventilation or work out of doors. Do not allow the FA to become excessively warm(eg, sitting in the sun) as this will shock the bees.We encourage beekeepers to experiment with this fumigator and with various formic acidformulations, in order to determine its efficacy and limitations. Please be careful and only workwith a few colonies at a time until we better understand its function under various conditions.Planned Future Work - We intend to conduct trials in the future using the 50% FAF inmore tropical conditions, hopefully in FL, and if funding becomes available, in some otherstates.ACKNOWLEDGMENTSThis research would not have been possible without a grant from SARE, USDA, and support bythe West Virginia University Experiment Station. Robert Noel’s late sister, Marlene Noel, gavehim the idea, and valuable inspiration for using essential oils to improve the health of the honeybee. Our colleague, Tony Delia, in West Redding Connecticut, provided much of the inspirationfor developing this formic acid fumigator. One of our greatest supporters for our mite researchover the years has been Vikram Prasad, M.D., West Bloomfield, Michigan. Many beekeeperfriends from throughout the US and Canada, and elsewhere have tried our fumigator and othermethods in our protocol and have given us positive results and many useful suggestions. Last,but not least, we owe a great debt to our families for supporting us and putting up with outfrequent absences throughout the past 11 years. To all, we give our deepest thanks.Published with the approval of the Director of the West Virginia Agricultural andForestry Experiment Station as Scientific Article Number 2952. This research was supported inpart with funds under the Hatch Act.FIGURE CAPTIONSFigs. 1-6. Details of the 50% formic acid fumigator (FAF). - 1, FAF standing on edge; 2.Top of FAF (Outside dimensions: 18" x 161/4" (45.72 x 41.275 cm)); 3. Bottom view ofFAF; 4. Side view details of FAF; 5. End view details of FAF; 6. The activation cavity